{
{     This request searches a files system buffer descriptor chain
{     for a byte address.
{
{  BAP$SEARCH_FOR_SB_DESCRIPTOR (KFT_DESCRIPTOR,BYTE_ADDRESS,SBD_PTR,STATUS)
{
{    KFT_DESCRIPTOR : (input) this parameter specifies the known file
{                      table entry.
{
{    BYTE_ADDRESS : (input) this parameter specifies the byte address to
{                    search for.
{
{    SBD_PTR : (output) this parameter specifies the system buffer descriptor
{               ordinal containing the byte address or NIL.
{               if NIL then the byte addess is not in the current system
{               buffer descriptor chain.
{
{    STATUS : (output) this parameter specifies request status.
